Brush seals are generally useful for axially segregating a plurality of adjacent annular fluid volumes in axial flow machines. For example, an axial flow gas turbine engine typically has a plurality of such adjacent volumes wherein it is desirable to maintain predetermined fluid volumes and/or pressures during machine operation.
More particularly, a brush seal provides this segregating effect by employing a flexible partition which is circumferentially disposed about and bears against the surface of a rotatable shaft, the partition bridging the gap between the shaft and its corresponding opposing surface. Effective partitioning by a brush seal occurs over a broad operating range by accommodating thermal and centrifugal growth, thereby maintaining desired fluid volume and pressure by limiting or preventing fluid inflow or outflow across the plane of the partition.
Brush seals of the prior art have a closed annular configuration comprising a pair of annularly shaped plates which capture a plurality of tightly packed bristles therebetween. The bristles are circumferentially arrayed about the annulus such that they project radially inwardly toward the rotational axis of the seal and shaft. Likewise, the outwardly-facing bristles of an outwardly facing brush seal bear against the inner surface of a structure disposed radially outward of the seal.
According to the prior art, the brush seal is installed about a rotatable shaft by axially sliding the seal along the shaft to its designated axial location and then affixing it at that location to a static structure using an appropriate attachment and retention method. This method of installation necessitates the time-consuming removal of those shaft-disposed machine elements with their associated hardware which are located in intermediary positions between the accessible shaft end and the designated brush seal location.